Peter Moyle, a fish biology professor at University of California Davis, looks over salmon spawning areas on Putah Creek in Davis CA., Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

Photo: Brian Baer, Special To The Chronicle

Peter Moyle, a fish biology professor at University of California...

Image 2 of 6

Peter Moyle, a fish biology professor at University of California Davis, looks over salmon spawning areas on Putah Creek in Davis CA., Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

Photo: Brian Baer, Special To The Chronicle

Peter Moyle, a fish biology professor at University of California...

Image 3 of 6

Peter Moyle, a fish biology professor at University of California Davis, looks over salmon spawning areas on Putah Creek in Davis CA., Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

Photo: Brian Baer, Special To The Chronicle

Peter Moyle, a fish biology professor at University of California...

Image 4 of 6

Peter Moyle, a fish biology professor at University of California Davis, sits inside his laboratory, Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

Photo: Brian Baer, Special To The Chronicle

Peter Moyle, a fish biology professor at University of California...

Image 5 of 6

Peter Moyle, a fish biology professor at University of California Davis, sits inside his laboratory, Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

Photo: Brian Baer, Special To The Chronicle

Peter Moyle, a fish biology professor at University of California...

Image 6 of 6

Peter Moyle, a fish biology professor at University of California Davis, works inside his laboratory, Monday Oct. 24, 2011. The alarming discovery in British Columbia of a contagious virus that has devastated salmon farms on the East Coast, in Europe, Chile and other places has angered conservationists who blame the aquaculture industry, but fishery scientists insist it is too early to panic.

The discovery in British Columbia of an infectious virus that has devastated salmon farms on the East Coast, in Europe and Chile has alarmed conservationists, some of whom blame the aquaculture industry, but fishery scientists say it is too early to panic.

The lethal virus, infectious salmon anemia, was detected in two of the 48 wild sockeye salmon tested during a Simon Fraser University study in Rivers Inlet, on the central coast of British Columbia.

The implication is that the disease could already be running rampant through the wild population of Pacific salmon, including California chinook and coho. The virus kills fish in as little as 10 days but has no effect on humans.

"The concern is that it could spread," said Richard Routledge, a Simon Fraser professor and environmental scientist who found the virus in tissue samples of smolts during an ongoing sockeye study that began in 2002. "Many of the wild salmon populations migrate along the continental shelf in the United States and Canada, and they presumably come in contact with each other."

The European strain of the virus, which until now had never been detected in salmon on the Pacific Coast, was confirmed this month by the Atlantic Veterinary College in Prince Edward Island. It was found in the heart tissues of the two sockeye and reported to the Canadian Food Inspection Agency, which is conducting an investigation.

The virus has devastated Atlantic salmon populations in Maine, Norway, South America and eastern Canada.

No vaccine, no cure

There is no vaccine or cure for the disease, which has always been associated with fish in offshore saltwater pens, where most of the Atlantic salmon sold in the United States comes from. The discovery of the virus among wild migrating sockeye has created a furor, especially considering that the Atlantic salmon being raised in exposed pens in British Columbia fjords and inlets are the most likely vectors.

Millions of Atlantic salmon eggs have been imported to the province over the last 25 years, primarily from Iceland and Scandinavia, officials said.

"The problem is you are raising salmon in pens and the sockeye are migrating past those pens, so it's very easy for them to pick up diseases from those pens," said Peter Moyle, a professor of fish biology at UC Davis. "We know it can happen. Salmon can pick up viruses in the water."

Fishery biologists in British Columbia warned against jumping to conclusions.

Jim Winton, the chief of the research section for the U.S. Geological Survey's Western Fisheries Research Center in Seattle, said some 4,000 penned Atlantic salmon have been tested over the past three or four years and no trace of the virus has been found.

"The question is, how did the virus occur in wild fish when the disease was not present in the salmon farms?" Winton said.

There are other possibilities, Winton said. He said some species of cod and other fish migrate across the Arctic Ocean and might have carried infectious salmon anemia to the Pacific. Fish and their diseases also frequently get transported in the ballast of ships, he said.

Previous tests have shown that some of the five species of Pacific salmon are less susceptible than Atlantic salmon to the disease.

Nobody really knows at this point whether the virus has spread, but Routledge is concerned because he had previously heard reports about fish showing symptoms of the disease. He said he took the samples after he and his students had a difficult time catching sockeye, an indication to him that the local fish population was in decline.

There are a lot of other reasons to be concerned, Moyle said, especially considering recent history. He said farmed Atlantic salmon have often escaped from their pens, sometimes through rips in the nets. Thousands were released during a storm in Norway several years ago, he said. Atlantic salmon are now regularly found in streams and the ocean in British Columbia, he said.

The mixing of wild and farm-raised fish is a worry because studies have documented wild fish with sea lice and other infections that were spread by farmed fish. Researchers have also documented fertility problems and less-robust offspring after wild fish have mated with hatchery fish, even after a generation in the wild.

Virus can mutate

The experts agree that the presence of the virus is bad news even if there is some immunity among Pacific salmon. The pathogen is a member of the orthomyxo family, which includes influenza. And, like the flu, infectious salmon anemia can mutate.

"This virus can mutate from a benign form to a particularly virulent one, and it has done this in the relatively recent past," Routledge said. "The implications could be very serious."

California does not practice fish farming the same way as British Columbia - the state's hatcheries raise fish for release into the wild - and Moyle said the California fishery does not appear to be in immediate danger. The virus could nonetheless be a death knell for the West Coast fishing industry, he said, were it to find its way into the state's signature chinook stock.

"Anytime you have a new disease that occurs, it could be devastating," Moyle said.